Total hip arthroplasty in patients with bone deficiency of the acetabulum.

Total hip replacement (THR) requires revision in only a minority of cases (approximately 17% of prosthetic hips fail), but when THR failures occur there may be significant acetabular bone deficiency. There is a variety of surgical hardware and strategies available to address this problem. The causes of primary THR revision include aseptic loosening or particle disease, infection, recurrent dislocation, implant failure, periprosthetic fracture, and leg length discrepancy. Almost all patients who need THR revision undergo a standard radiographic evaluation of the pelvis and hip. In general, CT is an excellent tool for evaluating loosening of the prosthesis caused by either mechanical reasons or infection, and MR imaging is best suited for evaluating the soft tissues surrounding the prosthesis. Nuclear medicine studies are performed when results of CT and MR imaging are inconclusive. When patients are evaluated for revision THR, radiologists must check for acetabular cup loosening, the amount and type of bone stock loss, the amount of component migration, and the presence or absence of liner wear. Before revision hardware is placed, bone stock loss must be repaired, either by using bone grafting or by placing accessory acetabular hardware such as cups, rings, or cages. The long-term success of revision acetabular surgery varies; there is acetabular cup presence at 5 years after surgery in 60%-94% of cases. Complications include postoperative infections, repeat liner wear, bone graft failure, periprosthetic or prosthetic fractures, dislocation, vascular injury, and nerve injury. Copyright RSNA, 2008.